To make the first proof-of-concept prototype, I see, that device should consist of two-three functional parts:

1) Antenna - which is designed/tuned to 2.4GHz (because it's standard frequency for mW-ovens). I'll try to use PCB antenna, due to 2 reasons: 1) cost reduction 2) IMHO more important: bigger surface area (I believe, the bigger area - the more energy can be collected)

2) Rectifier with voltage multiplier - with big probability the voltage on antenna pin will be very small to power even energy-harvesting ICs, which have their own "cold-start" voltage. Therefore we'll try to boost voltage.

3) Energy-harvester - circuit that makes energy storage, distribution and output more easy. I assume that this part at the moment is optional, because I'll be able to measure any voltage, detected by circuit, which consists of parts 1 and 2.